The terms “VDR” or “visual dynamic range” and “EDR” or “enhanced dynamic range” as used herein may refer to a dynamic range (e.g., 10,000 nits, 12,000+ nits, etc.) wider than a relatively low dynamic range such as a standard dynamic range (SDR), an intermediate high dynamic range (e.g., 1000 nits, 2000 nits, etc.), etc., and may include, but is not limited to, a wide dynamic range up to the instantaneously perceivable dynamic range and color gamut which human vision can perceive at an instant. Multiple layers may be used to deliver video data from an upstream device such as a multi-layer video encoder to downstream devices. For example, visual dynamic range (VDR) video data can be carried in the combination of a base layer and an enhancement layer (EL) of the multiple layers for viewing experience of VDR displays. BL image data may be encoded with low or partial dynamic range (e.g., SDR, an intermediate high dynamic range, etc.) image data derived from VDR images. EL image data may be encoded with residual image data which, along with image data predicted from the BL image data enables a downstream recipient system to reconstruct a version of the VDR images.
Different code words mapped from the VDR images may be collapsed into a same value in the BL image data representing a relatively low dynamic range such as an SDR image, an intermediate high dynamic range image, etc., at an upstream device. Textual variations and image details represented in the VDR images may be lost in the BL image data. When the recipient system performs a prediction operation from low bit depth BL image data to high bit depth VDR image data, contouring artifacts often occur in the high bit depth VDR image data as a result of one-to-many mappings in the prediction operation.
The approaches described in this section are approaches that could be pursued, but not necessarily approaches that have been previously conceived or pursued. Therefore, unless otherwise indicated, it should not be assumed that any of the approaches described in this section qualify as prior art merely by virtue of their inclusion in this section. Similarly, issues identified with respect to one or more approaches should not assume to have been recognized in any prior art on the basis of this section, unless otherwise indicated.